Apparatus and method for lining a pipe

ABSTRACT

An apparatus and a method for forming a lining in a pipe is disclosed. A pumpable material capable of curing is dispensed about an interior wall of a damaged section of pipe between an inflatable bladder and the pipe. The pumpable material is compressed between the bladder and the pipe and allowed to cure. An assembly for forming the lining in the pipe includes a feeding pump, a static mixer, a dispensing unit and a bladder. The pumpable material is preferably dispensed rearward of an inverting face of the bladder and the dispensing unit and the bladder move substantially in sync along the interior of the pipe.

BACKGROUND OF THE INVENTION

The present invention relates to an apparatus and method for lining aninterior surface of a pipeline.

A method presently used for repairing pipelines includes the use of aliner tube having a felt layer on its inside and having a protectivelayer made of polymer or other plastic material on its outside. Theliner tube is vacuum-impregnated with a resin mix in what is commonlyreferred to as a “wet-out” process. Just prior to wetting-out the liner,a catalyst is mixed with the resin so as to activate the resin and causeit to begin curing and hardening. The resin impregnated liner tube isthen inverted into the pipeline so that the felt layer is inverted fromthe inside of the tube to the outside. Once the resin cures and hardens,the liner provides a new lining for the pipeline. Some resins are set tocure at ambient temperatures. In some instances, steam or hot water isapplied inside the lining tube to speed the cure time

One problem with the present method is that the catalyst must be mixedwith the resin before the liner tube is wet-out and before positioningthe liner tube at the damaged section of pipe. Once the catalyst isapplied to the resin, the resin begins curing and time is of the essencein order to have the liner tube in place within the pipeline to berepaired. If the resin hardens before the liner tube is properlypositioned within the pipe, it may require that a portion of theexisting pipeline be dug up and replaced. If, on the other hand, a resinmix with a longer cure time is used to ensure adequate working time toinstall the liner, productivity suffers as the crew waits for the linerto cure and harden.

Aside from the loss in productivity, there are also additional costsinvolved in retarding or accelerating the cure time. For example,following the wet-out process the lining tube can be packed in ice andstored in a refrigerated compartment of the truck to retard or preventthe resin from curing. To accelerate the cure time, a large boiler andother equipment is required at the job site. Such equipment and theassociated labor required all adds to the total installation cost.

Some attempts have been made to spray or sling grout onto the interiorsurface of the pipe. Such methods are also problematic. Spraying orslinging grout inside the pipe does not provide for a uniform wallthickness of the lining. The grout or other material applied will alsotend to run away from the crown of the pipe and toward the bottom of thepipe before the material can cure and harden. This sagging effectresults in the uneven distribution of lining material around theinterior of the pipe. The lining also does not have a smooth surface.Still further yet, the spraying or slinging method is not effective inareas of the pipe where there is ground water infiltration. Problemsstill certainly remain.

Use of a pre-formed liner tube itself can be problematic. For example,the liner tube is normally fabricated off-site in a factory and thus thedimensions of the host pipe and the section of pipe in need of repairmust be known in advance to construct a liner of appropriate size.Conventional liners are also susceptible to shrinkage and otherstructural problems.

Therefore, a primary object, feature and/or advantage of the presentinvention is the provision of an improved method for forming a liner ina pipeline.

A further object, feature and/or advantage of the present invention is anew apparatus and method for lining a pipe that does not require apre-formed liner tube.

A further object, feature and/or advantage of the present invention isthe provision of a new method that provides a pipe lining having asmooth surface with a uniform wall thickness.

A still further object, feature and/or advantage of the presentinvention is the provision of the new lining system that is unaffectedby ground water and other materials in the host pipe.

A further object, feature and/or advantage of the present invention is anew lining method that allows for extremely fast cure times to greatlyimprove productivity.

Yet a further object, feature and/or advantage of the present inventionis the provision of a new method of pipe line repair that is flexible inallowing any length of lining to be installed during the installationprocess without pre-fabrication of a liner of a desired length.

A still further object, feature and/or advantage of the presentinvention is the provision of a new method and means for lining that ismore cost-effective than prior art methods.

These and/or other objects, features and/or advantages of the inventionwill become apparent with reference to the remainder of thespecification and claims.

BRIEF SUMMARY OF THE INVENTION

One aspect of the invention includes a method of rehabilitating adamaged section of pipe that obviates the need for a pre-formed liner.The method generally includes dispensing a pumpable material capable ofcuring about an interior wall of the damaged section of pipe between abladder and the pipe, compressing the bladder against the damagedsection of pipe with the pumpable material disposed between the bladderand the pipe, and allowing the pumpable material to cure.

In a preferred form, the bladder is inverted in the pipe and thepumpable material is dispensed rearward of an inverting face of thebladder using a dispensing unit. The pumpable material, such as a resinmix including a resin and a catalyst, is dispensed evenly about theinterior wall of the damaged section of pipe. Dispensing the pumpablematerial rearward of the inverting face of the bladder as the bladderinverts along the pipe prevents the pumpable material from sagging tothe bottom of the pipe and provides a lining having a uniform wallthickness with a smooth interior surface. The inverting face of thebladder is substantially in sync with the dispensing unit to ensure thatthe pumpable material is dispensed rearward of the inverting face of thebladder.

In one exemplary embodiment of the invention, the bladder is removedfrom the damaged section of pipe once the pumpable material fully cures.A non-stick bladder facilitates easy removal of the bladder as it isre-inverted from host pipe, pulling away from the new pipe lining.

In an alternative embodiment, the bladder remains in the pipe, becomingpart of the lining. Here, it is preferable that the exterior surface ofthe bladder once inverted is uneven and includes projections adapted tomechanically bond the pumpable material to the bladder after thepumpable material cures, thus creating both an adhesive bond and amechanical bond to hold the bladder in place.

Another aspect of the invention includes an assembly for lining aninterior of a pipe that includes a feeding pump, a static mixer in fluidcommunication with the feeding pump for mixing a pumpable materialcapable of curing, such as a resin and a catalyst to form a resin mix. Adispensing unit is in fluid communication with the outlet of the staticmixer. The dispensing unit includes a nozzle adapted to dispense thepumpable material evenly around the interior of the pipe. The bladder isadapted to compress the pumpable material against the interior of thepipe. The dispensing unit is operatively connected to a first reel andfirst motor and the bladder is operatively connected to a second reeland second motor and wherein the first and second reels areelectronically controlled in order to control the rate at which thebladder and the dispensing unit move along the interior of the pipe. Thedispensing unit preferably includes a flexible end portion adapted tomove around irregular surfaces or projections on the interior of thehost pipe.

The present invention contemplates repair of all kinds of pipelinesincluding, but not limited to, mainline sewer pipelines, lateral sewerpipelines, gas pipelines and water pipelines.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A is a schematic view illustrating a preferred embodiment of thepresent invention utilized for repairing a mainline pipe extendingbetween two manholes.

FIG. 1B is a schematic view similar to FIG. 1A, further illustrating thepreferred lining process of the present invention.

FIG. 2A is an enlarged side view of a tractor and resin dispensing unitwith nozzle for use in a preferred embodiment of the present invention.

FIG. 2B is an end view of the nozzle of the dispensing unit.

FIG. 3 is a sectional view of a potable water pipe with corporationstops after having been lined according to a preferred embodiment of thepresent invention.

FIG. 4 is an enlarged sectional view of a pressurized reel with bladderloaded therein for use in a preferred embodiment of the presentinvention.

FIG. 5 is a sectional view of a sewer pipe with a damaged section ofpipe lined according to a preferred embodiment of the present invention.

FIGS. 6A-6C are enlarged sectional views, illustrating various forms ofa bladder for use in an alternative embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1A, a main pipeline 64 is shown extending between adownstream manhole 62 and an upstream manhole 60. While the presentinvention is shown for use with sewer pipeline repair, the presentinvention can be utilized for repairing other types of pipe, such asgas, water, oil, steam and compressed air pipe.

Adjacent the downstream manhole 62 is a truck 58 having resin pump A 70and a reservoir A 72 and catalyst pump B 76 and a reservoir B 78 mountedthereon. Hose 68 and hose 74 extend from the reservoirs A 72 and B 78,respectively, down to a static mixer 28 housed within a small tractor 10shown within the pipeline 64. The hoses 68 and 74 may also includeelectronic cables for controlling the tractor 10.

FIG. 2A shows the tractor 10 and dispensing unit 25 extending therefrom.Tractors such as the one shown are commonly used in the pipeline repairindustry and are capable of moving along the length of the pipeline 64.The tractor 10 shown includes a tractor housing 12, wheels 20 andcameras 54. The static mixer 28, disposed within a static mixer housing14, is positioned within the tractor housing 12. The dispensing unit 25comprises a nozzle which is fluidly connected to an output 22 from thestatic mixer 26 for applying a resin mixture on the interior of thepipeline 64. The nozzle of the dispensing unit 25 includes a rigidsection 24 and a flexible end portion 26. The flexible end portion 26 isformed of a material like rubber and, if necessary, can be removed andreplaced after each application. As shown in FIGS. 2A and 2B, the nozzleof the dispensing unit 25 is formed with funnel-shaped members offsetfrom one another leaving a space therebetween for even distribution ofthe resin mixture around the periphery of the nozzle.

A two-part resin including a resin with a catalyst is an example of apumpable material capable of curing that is suitable for use with thepresent invention. The preferred resin mixture is an epoxy resin set ata 1:1 resin to catalyst mix ratio, Rhino Linings product no. 1310T.Rhino Linings is located at 9090 Kenemar Drive, San Diego, Calif. USA92121. A single component resin, such as a UV cured resin, could also beused. Other pumpable materials for use with the invention include motor,grout, and modified liquid materials capable of hardening and producinghigh flexural and tensile properties. Modifiers include noncarbon tubesand similar structural enhanced additives.

The preferred two-part resin is pumped from pump A 70 and pump B 76 toinputs 16 and 18 of the static mixer 28. The resin is fed via hose 68 toinput 16 and the catalyst is fed via hose 74 to input 18 and completelymixed within the static mixer 28. The resulting mixture is distributedfrom output 22 of the static mixer 28 and through the dispensing unitonto the interior surface of the pipeline 64. The flexible end portion26 of the nozzle of the dispensing unit 25 is preferably biased radiallyoutwardly so as to maintain contact with the interior wall of thepipeline 64.

Static mixers incorporate a series of geometric mixing elements that aremade from metal or a variety of plastics fixed within a cylindrical(tube) or squared housing, which use the energy of the flow stream tocreate mixing between two or more fluids. Likewise, the mixer housingcan be made from metal or plastic. Typical materials of construction forthe static mixer components include clear PVC, gray PVC, stainlesssteel, ductile iron, polypropylene, Teflon, Kynar, fiberglass andpolyacetal.

Hoses 68 and 74 are wound through a take-up reel 80 outside and abovethe downstream manhole 62. The hoses 68 and 70 are banded as designatedby the reference numeral 110. In addition to acting as a conduit for thepumpable material, the banded hoses 110 also help to properly positionand move the dispensing unit 25 along the pipeline 64. The take-up reel80 controls the length the banded hoses 110.

Outside and above the upstream manhole 60 is a pressurized reel 30 whichcontains an outer cylindrical housing 32 and a center roller 34. Apressure inlet valve 36 in the housing 32 provides communication fromthe interior of the housing to a pressure hose 38. Pressure hose 38 ispreferably connected to a pneumatic source of pressurized air. However,other fluids could be used without detracting from the invention.

The pressurized reel is shown in greater detail in FIG. 4. The valve 36is movable from an open position permitting pressurized fluid(preferably air) to be introduced to the interior of pressurized reel 30to a closed position shutting off communication of pressurized fluidfrom the interior of the pressurized reel 30. The reel 30 includes aninverting boss 40 on one of its sides upon which may be mounted aninflatable bladder tube designated generally by the numeral 42.

The bladder tube 42 is preferably formed from a fiber reinforcednon-stick plastic material, which allows the bladder tube 42 to beeasily removed from the cured lining material when re-inverted throughthe pipeline 64. The bladder tube 42 preferably includes a body formedof a layer of fiber reinforcing material, such as a scrim reinforcingfabric. The layer of fiber reinforcing material is preferably a scrim ofNylon filament knit fibers. The body has an inside coating and anoutside coating, both preferably made of a thermoplastic elastomer. Anexample of a commercial TPE elastomer alloy found suitable isSantopreene® from Monsanto. The wall thickness of the bladder ispreferably 15-30 mils.

Referring again to FIG. 4, a rope 52 is wound around the center roller34 within the pressurized reel 30. Sufficient rope must be included togo the entire length of the damaged portion of the pipeline 64 to berepaired. The closed end 50 of the bladder tube 42 is attached to theend of the rope 52. The bladder tube 42 is then wound around the centerroller 34 until its complete length is taken up. The open end 48 of thebladder tube 42 is fitted over the boss 40 and is taped or clamped inplace so as to have an airtight connection therearound. As shown in FIG.4, the open end 48 of the bladder tube 42 is folded back upon itselfmuch in the same fashion as the peeling off of a sock.

In operation, the bladder tube 42 must be properly positioned initiallyrelative to the dispensing unit 25. A length of the bladder tube 42 isdropped into the upstream manhole 60 adjacent the opening to the mainpipeline 64. An operator in the manhole 60 can then position theinverting face 56 of the bladder tube 42 inside the nozzle of thedispensing unit 25. The inverting face 56 of the bladder tube 42 shouldextend into the nozzle past the end portion 26 where the resin mix isdispensed. The valve 36 is then moved to its open position and fluidpressure, preferably air, as introduced into the interior of the reel 30such that the bladder tube 42 inflates and the pull rope 52 becomestaught. Similarly, the banded hose lines 110 running to the tractor 10are also pulled taught by the take up reel 80. The resin and catalystare then pumped from the truck 58 through lines 110 and through thestatic mixer 28 and out the end portion of the dispensing nozzle 26.

Once an operator visually confirms that the resin mix is dispensingthrough the end portion 26 of the dispensing unit 25, the reels 80 and30 are put into a sync mode such that the dispensing unit 25 travels atsubstantially the same pace and is in synch with the inverting face 56of the bladder tube 52. The reels 80 and 30 are smart reels thatcommunicate electronically with each other through a data cable 82. Eachreel is operatively connected to a motor. The motors are preferably DCmotors, and one of the motors may be positioned within the pressurizedreel vessel. It is preferable that the rotational speed of the take upreel 80 be slightly less than the rotational speed of the pressurizedreel 30, as this avoids the inverting face 56 of the bladder tube 42 andthe dispensing unit separating. The force applied by the invertingbladder tube 42 helps push the dispensing unit through the pipeline 64as the reel 80 takes up the slack in the banded hose lines 110.

FIG. 1A shows a small section of the resin mix applied around theinterior of the pipeline 64. The resin is dispensed from the flexibleend portion 26 of the dispensing unit 25 rearward of the inverting face56 of the bladder tube 42. This has several advantages. It avoids simplypushing the resin mix forward along the pipeline 64. Also, it preventsthe resin mix from sagging and running toward the bottom of the pipeline64. Instead, the resin mix is dispensed between the inverted bladdertube 42 and the host pipe 64 with the bladder tube compressing the resinmix against the pipe. This provides for an even distribution of resinmix around the interior wall of the host pipe 64 and a smooth, uniformwall thickness for the lining 66. The combination of the flow rate ofthe resin mix and the rate at which the dispensing unit travels alongthe pipe determines the wall thickness, as the present inventionessentially extrudes the pipe in the host pipe.

FIG. 1B shows the dispensing unit and bladder tube after the assemblyhas moved along a portion of the pipeline 64. The service connections tothe lateral pipes 65 must be later reinstated using a robotic cutter orthe like. Using a bladder tube 42 having a reinforced scrim, aspreviously described, limits the expansion of the bladder tube whenotherwise unconstrained at the lateral service connections. Once thedesired length of lining is applied to the pipe, the bladder tube canstop inverting and pressure within the bladder is maintained until theresin mix fully cures and hardens. Those skilled in the art willappreciate that because of the catalyst is introduced using a staticmixer 28 immediately prior to dispensing the resin mix around theinterior of the pipe 64, a resin mix having a very short cure time atambient temperatures can be used, thus greatly improving productivityand cycle time for the operation.

In a preferred form of the invention, the bladder tube 42 is removedafter the resin mix has cured and hardened. The bladder tube is removedby pulling the rope 52, which reinverts the bladder tube 42. The easyremoval of the bladder tube 42 is facilitated by the use of a non-stickbladder, as previously described.

In an alternative embodiment of the preferred lining method, the bladdertube 42 is not removed from the host pipe 64. Instead, the exteriorsurface 102 of the bladder tube 42 is uneven or irregular in shape,which facilitates a mechanical bond between the cured resin mix and thebladder tube 42. FIG. 5 shows a section of the finished lining with thecured resin mix 94 and bladder 92. The enlarged sectional views 6A-6Cshow the exterior surface 102 of the bladder tube 42 includes variousprojections 106 which can be used to physically trap the cured resin.These hook-like projections or protrusions 106 upon trapping the curedresin create a mechanical bond between the resin and the bladder tube42. Once the resin has set, a closed end portion of the bladder tube canbe cut out to reinstate service through the pipe 64. In this embodiment,the bladder becomes an impermeable coating for the lining.

As described previously, the flexible end portion 26 of the nozzle ofthe dispensing unit 25 is biased outwardly so as to maintain contactwith the interior of the host pipe. Providing a flexible end portion 26also allows the dispensing unit 25 to accommodate changes in diameterinside the pipe and various protrusions. Consider, for example, apotable water pipe 84, as shown in FIG. 3. Corporation stops 88 connectthe service water lines 90 with the potable water pipe 84. The ends ofthe corporation stops 88 are threaded and protrude into the host pipe84. The flexible end portions 26 allow the dispensing unit to easilymaneuver around the corporation stops 88 to dispense a lining 86.

Those skilled in the art, having the benefit of this disclosure, willappreciate the numerous advantages achieved by the present invention. Ofcourse, no pre-formed liner is required. In addition, the presentinvention avoids the problems associated with wetting out a liner andeither retarding or accelerating the cure rate to accommodate the“working” time. Workers are often constrained by working time. There islimited amount of time to get the liner in place after the resin ismixed. The liner must be wetted out and installed before it cures. Oncethe liner is properly positioned within the pipe, then it is preferableto speed up the curing process, which may be done by introducing steam,heat, etc. Using the present invention, the wet out process essentiallyoccurs within the pipe and a fast cure time is therefore appropriate.That is, the use of the present invention enables an aggressive cureschedule, which greatly improves productivity. And because a fast curetime can be used with the resin mix in the present invention, the resinmix will quickly become highly viscous, further avoiding the problemsassociated with sagging at the bottom of the pipe.

In the drawings and specification there has been set forth a preferredembodiment of the invention, and although specific terms are employed,these are used in a generic and descriptive sense only and not forpurposes of limitation. Changes in the form and the proportion of partsas well as in the substitution of equivalents are contemplated ascircumstances may suggest or render expedient without departing from thespirit or scope of the invention as further defined in the followingclaims.

1. A method of rehabilitating a damaged section of pipe that obviatesthe need for a pre-formed liner, the method comprising: dispensing apumpable material capable of curing about an interior wall of thedamaged section of pipe between a bladder and the pipe; compressing thepumpable material disposed between the bladder and the pipe; andallowing the pumpable material to cure.
 2. The method of claim 1 furthercomprising removing the bladder from the damaged section of pipe.
 3. Themethod of claim 1 wherein the bladder is inverted in the pipe.
 4. Themethod of claim 1 wherein the bladder moves substantially in sync with adispensing unit along the damaged section of pipe as the dispensing unitdispenses the pumpable material.
 5. The method of claim 4 wherein thebladder is inverted in the pipe and dispensing unit dispenses thepumpable material rearward of an inverting face of the bladder.
 6. Themethod of claim 5 wherein the dispensing unit includes a flexible endportion adapted to move around irregular surfaces on the interior of thedamaged section of pipe.
 7. The method of claim 1 wherein the pumpablematerial is a resin mix comprising a resin and a catalyst.
 8. The methodof claim 1 wherein the pumpable material is dispensed evenly about theinterior wall of the damaged section of pipe.
 9. The method of claim 1wherein the pumpable material is a cementitious material.
 10. A methodof rehabilitating a damaged section of pipe that obviates the need for apre-formed liner, the method comprising: inverting a bladder in thedamaged section of pipe; dispensing a pumpable material capable ofcuring about an interior wall of the damaged section of pipe behind aninverting face of the bladder between the bladder and the pipe; movingthe inverting face of the bladder substantially in sync with the adispensing unit along the damaged section of pipe as the dispensing unitdispenses the pumpable material; compressing the pumpable materialdisposed between the bladder and the pipe; and allowing the pumpablematerial to cure.
 11. The method of claim 10 wherein the pumpablematerial is a resin mix comprising a resin and a catalyst.
 12. A methodof rehabilitating a damaged section of pipe that obviates the need for apre-formed liner, the method comprising: inverting a bladder in thedamaged section of pipe, the bladder having an exterior surface wheninverted being uneven; dispensing a pumpable material capable of curingabout an interior wall of the damaged section of pipe behind aninverting face of the bladder between the exterior surface of thebladder and the pipe; moving the inverting face of the bladdersubstantially in sync with the a dispensing unit along the damagedsection of pipe as the dispensing unit dispenses the pumpable material;compressing the pumpable material disposed between the bladder and thepipe; and allowing the pumpable material to cure.
 13. The method ofclaim 12 wherein the exterior surface of the bladder being adapted tomechanically bond the pumpable material to the bladder after thepumpable material cures.
 14. The method of claim 13 wherein the exteriorsurface of the bladder includes projections adapted to mechanically bondthe pumpable material to the bladder after the pumpable material cures.15. The method of claim 14 wherein the exterior surface of the bladderincludes hook-like projections adapted to mechanically bond the pumpablematerial to the bladder after the resin cures and hardens about theexterior surface of the bladder.
 16. The method of claim 12 wherein thepumpable material is a resin mix comprising a resin and a catalyst. 17.The method of claim 12 further comprising removing an end portion of thebladder after the pumpable material has cured.
 18. An assembly forlining an interior of a pipe comprising: a feeding pump; a static mixerhaving an inlet and an outlet, the inlet being in fluid communicationwith the feeding pump for mixing a resin and a catalyst to form a resinmix; a dispensing unit in fluid communication with the outlet of thestatic mixer, the dispensing unit having a nozzle adapted to dispensethe resin mix evenly around the interior of the pipe; a bladder adaptedto compress the resin mix dispensed from the dispensing unit against theinterior of the pipe; wherein the dispensing unit operatively connectedto a first reel and first motor and the bladder operatively connected toa second reel and second motor, the first and second reels areelectronically controlled to control the rate at which the bladder andthe dispensing unit move along the interior of the pipe.
 19. Theassembly of claim 18 wherein the bladder is adapted to movesubstantially sync with the dispensing unit along the interior of thepipe.
 20. The assembly of claim 18 wherein the nozzle includes aflexible end portion adapted to move around irregular surfaces on theinterior of the pipe.